Electrolytic apparatus



ELECTROLYTIC APPARATUS Filed Apr. '7, 1921 l 311mm dofo Registered Mar. 27, 1923.

UNITED STATES JAMES NORMAN SMITH, OF TORONTO, ONTARIO, CANADA.

ELECTROLYTIC APPARATUS.

Application led April 7, 1921. Serial No. 459,293.

To all whom 'it may concern Be it known that I, JAMES NORMAN SMITH, a citizen of Dominion of Canada, residing at Toronto, in the county of York and Province of Ontario, Cana-da, have invented certain new and useful Improvements in Electrolytic Apparatus; and I do hereby declare the following to be a. full, clear, and exact description of the inventlon, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electrolytic apparatus, useful in carrying on various electrolytic processes such, for example, as electrolysis of saline solutions, electrolytic production of oxygen and hydrogen, electrodeposition of metals, and the like. For the sake of a concrete example, apparatus adapted especially for use in generating oxygen and hydrogen electrolytically will be more particularly hereinafter described, but 1t 1s to be understood that the principles of the invention can be embodied in apparatus applicable to various other purposes in the electrolytic art, including those mentioned above.

The inventionhas to do especially with diaphragmless electrolytic generators of the general character and principle of operation disclosed in the co-pending (loint application of myself and Farley r. Clark, Serial No. 459,292, filedI April 7, 1921. The present invention involves certain further developments of and improvements upon the apparatus disclosed in said application.

Generally described, the apparatus forming the subject matter of said co-pending application comprises cooperating electrodes whose active surfaces are of relatively small transverse width and are arranged relatively close together, most desirably with no diaphragm interposed therebetween. Electrolyte is caused to flow at relatively high velocity between and across the opposed elec trode faces. which for best results i-n generatingl oxygen and hydrogen are not more than sa'v one-tenth of an inch apart, and which may be even much closer together. In employingthe apparatus for other pur` poses, as in electrolyzing salt brine, for example, the electrodes may be farther apart, a spacing distance of one-fourth inch or so being often satisfactory. In fact, the invention in its broader aspects is not limited as to the distance of the electrodes apart. Immediately after passage across the narrow electrolyzing zone formed between the active electrode faces, the swiftly moving flat body or layer of electrolyte impinges upon the thin edge of a separating or dividing device which divides or splits the bod-y of electrolyte into anolyte and catholyte portions before interdiffusion of the anodic and cathodic products can occur to a substantial extent. Where it is not desired to maintain the anodic and cathodic products separate and to collect them in substantially pure condition, division of the electrolyte into anolyte and catholyte portions after passage through the electrolyzing zone is not essential, and the means for eifecting this division may accordingly -be omitted.

The apparatus of the present invention is of the general type just described; but it involves an arrangement of a plurality of cell or generator units, each of the general character above set forth, in a unitary apparatus in such a way as to greatly increase the output capacity of apparatus of a given size, the novel construction embodying also other desirable features and obtaining certain other desirable ends, as will hereinafter appear.

In order to afford a full understanding of the principles underlying the invention, a desirable practical form of apparatus embodying the principles thereof is illustrated in the accompanying drawings andis described hereinafter in detail. Itis to he understood, however, that .this illustrative embodiment is merely typical of apparatus coming within the broad scope of the invention, and that the invention is not limited to the particular details of construction shown and described. In the drawings referred to,

Fig. 1 is a central vertical section through an electrolytic cell or generator constructed in accordance with the invention;

Fig. 2 is a central horizontal section of the same, parts being shown in elevation; and

Fig. 3 is a fragmentary view, partly in section, of another advantageous arrangement of electrodes comprising a single couple or unit.

Referring to the drawings, the generator comprises a casing composed of concave end (in this instance top and bottom) members or sections 10 and l1, and an intermediate assembling bolts 13.

annular member or section 12, all of which members, together with other parts hereinafter mentioned, are secured together in a structural unit by means 4of suitable fastening means such as bolts 13 passing through suitable apertures in peripheral flanges 11, 15, with which said end members and the intermediate section member are respectively provided. In the practical form of apparatus here shown, the generator casing is substantially circular in horizontal plan; but the particular shape thereof is not es- -sential to the invention. The space within said casing is divided by two partition walls 16 and 161 into a central4 chamber 17, and end chambers 18 and 19. The margins of said partitions` are apertured to receive the The partition walls 16 and 161 serve respectively to support a plurality of pairs of cooperating anode members 20 each having an annular edge 22, and cathode members 21 eachy having an annular edge 22a, each pair or couple of such electrodes constituting a generator unit within the meaning of the language hereinabove used. In the present example, each generator unit is substantially of the construction disclosed in the co-pending application of Clark and Smith aforesaid and such generator units Aare not claimed herein.l but form the subject matter of said copending application. That is to say, each electrode is hollow, of bell-like form internally, and circular in cross-section, the two menibers of each pair being positioned with the bell edges 22 and 22a closely adjacent to provide an annular electrolyzing zone of comparatively small transverse width. Moreover, in the best `embodiment of the invention as applied to an electrolytic generator of oxygen and hydrogen, the bell edges or active electrode surfaces 22 and 22rl of each cooperating couple are advantageously not more than say one-tenth of an inch apart, and the annular slot-like space between them is free and unobstructed. In the present instance, the pla-ne of the annular slot thus formed between the cooperating electrodes of each pair is horizontal, and the cathode of each unit is uppermost; but although this arrangement is desirable for reasons pointed out hereinafter, it is not essential in the broader aspects of the invention. The position of the anode and cathode may be reversed, andjthe annular slot may -be in aI vertical or other plane. Moreover it isfnot essential that the slot be annular.

The mounting of the electrodes in the par- .i tition walls 16, and the assemblage of the latter with the casing members or sections,

may be variously accomplished. Whatever form `of ,mounting is employed, provision should be made to electrically insulate said end members or sections from each other and also to ensure a metallic path for current from each terminal to its corresponding set of anodes or cathodes as the case may be. The mounting of each of the anodes and cathodes in the cross partitions or supporting Walls may be generally similar. The electrol zing current is in this instance supplied to e anodes and cathodes by Way of terminals 23 and 24, which are secured respectively in good electrical contact with the end casing members 11 and 10, the respective flanges of which latter bear directly against annular metal plates 25 and 25n through which bolts 13 also pass. It is to be noted that the bolts 13 areencased in insulating bushings 13a. The joint between each flange 14` and the contiguous plate 25 or 25a may be made tight by means of an annular gasket 141 disposed in registering grooves formedv in the matingY faces of the -flange yand plate.

In the case of each anode, the reduced tubular stem or neck 26 projects through a suitable aperture in the partition 16, and through a similar aperture in the annular metal plate 25 on the lower side of the partition. The projecting portion of each anode stem or neck is externally threaded to receive a locking nut 27 which can be turned down solidly against the plate 25, thereby drawing the external annular shoulder 28 of the electrode firmly against the other side of the partition. Insnlating material 29 insulates the partition 16 from the intermediate casing section 12 and incidentally also from the adjacent plate 25 and from the set of anodes carried by said partition.

T he mounting of the cathodes in partition 161 is similar to the mounting of the anodes, but the positions of said cathodes are reversed relatively to the anodes. The reduced neck 26 of each cathode projects upwardly through an aperture in the partition 161, and through an opening in an annular plate 25 on the upper side of the partition. The neck is threaded for the reception of a nut 27a, by nieansof which a shoulder, 28a, is drawn into intimate contact with the underside of the partition, and the electrode is rmly positioned in the partition 161 and the plate 25a. The partition 161 is insulated from the annular plate 25-, the section' 12, and the cathodes, by means of insulating material 29a. The active electrode surface 22a of each cathode will be in proximity to and parallel with the active surface 22 of an anode 20, and space between the member 30 and the wall 33a of the cathode will permit of the escape of hydrogen and catholyte from the chamber 17.

It will be seen that by virtue of the described arrangement the end member 10 and the cathodes 21 electrically connected thereto are effectively insulated from. end memberfll and the anodes 2O electrically connected thereto; while at the same time a Cil metallic path is provided from each terminal, 23, 24, to its corresponding set of electrodes.

Closely adjacenteither the inner or the outer edge of the slot-like passage formed between the faces 22, 22a of each electrode couple 20, 21, is located means for dividing into anolyte and catholyte portions the layeriform body of electrolyte that flows across the electrolyzing zone between the active elect-rode surfaces 22, 22a. 1n the particular form of the invention here shown, the dividing element is located within the generator unit and comprises a thin-edged disc 29h, which may be 'of insulating material, clamped between upper and lower members 30 and 31 which are generally of conical form but whose surfaces are curved as indicated at 32 in such a way as to diverge slightly from the correspondingly curved inner surfaces 33- and 33 of the co-operating electrode members, in a direction away from the vslot formed between the active electrode surfaces. Any suitable means may be provided for securing the members 30and 31 together with the disc 29h clamped between them, but in the typical construction illustrated in Fig. 1, the lower member 31 is provided with a threaded stem 31a projecting through a central opening in the disc 29h, said stem being engaged by a nut 34 of insulating material, said nut being threaded also externally for engagement by a cooperating threaded recess formed in the upper member 30. Each lower separator member 31 has an elongated stem 32a which extends through an insulating bushin 33a screwed in the wall of casing 11, sai stem having a threaded engagement with said bushing whereby the separator device as a whole can be adjusted vertically as may be necessary to secure the optimum separation or division of the flowing electrolyte into anolyte and catholyte portions. A lock nut 34 is provided to hold the device in any adjusted position. The packing gasket 35 makes a tight joint between the screw threaded bushing 33a and the casing wall. The upper portion of the separator device is properly centered in the longitudinal axis of the cooperating electrode pair by means of radial centering or spacing pins 36, or other appropriate means.

An inlet pipe 37 entering the intermediate chamber 17 through the wall Aof the intermediate section 12 provides means for introducing electrolyte under pressure from any suitable source into chamber 17, which serves as an electrolyte supply chamber common to all the generator units, four in this case. Outlet pipes 38and 39, are provided for conducting oxygen and anolyte from end chamber 18, and catholyte and hydrogen from the end chamber 19.

The manner of employing the apparatus described is for the most part apparent from the foregoing description, but for the sake of clearness it will be summarized briefly. 1V here the apparatus is employed for 'the electrolytic generation of oxygen and hydrogen from water, the electrolyte may be either an aqueous solution of an acid or an alkali of the proper concentration to give an electrolyte of minimum resistance. Ordinarily it is most desirable to employ a caustic soda solution of about 17 per cent strength, or caustic potash solution of about 30 per cent strength. In order to ensure flow of the electrolyte between the active electrode surfaces at a sufficiently high velocity, there should be a substantial drop in pressure between the points at which the electrolyte enters and leaves the electrolyzing Zone. In a typical instance this dropy may amount to say one pound or more, although the absolute amount may vary considerably in practice within the invention. The electrolyte is introduced through inlet 37 into the chamber 17 common to all the generator units under a pressure head adequate to force it to flow at a sufliciently high velocity between lthe active electrode surfaces of the several pairs of cooperating electrodes. Suitable voltage is applied to the terminals 23, 24 from the current supply mains to provide an electrolyzing current of which the density may be, for example, from 5 to 50 amperes or more per square inch of projected electrode area, that is, per square inch of the cross-sectional area of the current path between the annular active electrode surfaces22 and 22a. Notwithstand ing the absence of a separating diaphragm, there need be substantially no interdiifusion of generated hydrogen and oxygen during the very brief period required for the swiftly flowingl electrolyte to traverse the narrow width of the electrolyzing zone; and immediately upon leaving said zone, the effluent electrolyte impinges upon the sharp edge of the separator disc 29b and is thereby divided into anolyte and catholyte portions. By reason of the fact that the volume of hydrogen generated is twice that of the oxygen, it is sometimes of advantage to adjust the position of the separator device in such manner as to bring the plane of division slightly closer to the anode than to the cathode. After division of the inflowing electrolyte in this way, thel anolyte and catholyte travel separately and in opposite directions through the gradually enlarging annular channels each formed between the surfaces of the separator 30, 31 and inner 'electrode walls, respectively, and then pass out into the anolyte and catholyte chambers 18 and 19, respectively, the ve locity of flow being very greatly reduced ,in the meantime, thereby giving opportunity for coalescence of the fine gas particles and partial separation of gas from the electrolyte. The anolyte carrying with it bubbles of oxygen passes out through discharge outlet 38 and may be conducted thence to suitable tanks for separation of the oxygen from the anolyte; while cathow lyte and hydrogen are discharged through outlet 39 and may go Asimilarly to appropriate apparatus for separating catholyte and hydrogen. In general, apparatus suitable for effecting this separation is well known in lthe art, and since the detailed character of 'the same forms no part of the present invention, a description thereof is unnecessary here.l A typical system suitable for the purpose is illustrated however, in the aforesaid application of lark and Smith.

The outer cylindrical surfaces of the electrode members are shown in the present eX- ample as covered with insulating material 39, said faces thereby being electrically isolated from the surrounding electrolyte. This is desirable in that it aids in confining the electrolyzing effect of the current strictly to the zone bounded by the cooperating activ surfaces 22, 22a of each pair. 'Y

By disposing the cathodes above and the anodes below a horizontal plane of division, as in the speciic arrangement herein disclosed, advantage is taken of the very low specific gravity of hydrogen, as compared with that of oxygen, to further guard against the possibility of hydrogen diffusing into the oxygen. This is a matter .of some practical importance where it 1s desirable to9 obtain particularly pure oxygen.

In the construction shown in Fig. l, the active or working surfaces of the anode 'and cathode 20, 21, are of substantially equal area. It is desirable in some instances to employ la generator unit in which the cathode -has a greater working surface than the anode. One practical -form of construction by which this may be accomplished is illustrated in Fig. 3, where the cylindrical body portion of the cathode 40 is of somewhat greater diameter than that of the anode 41, so that the active surface 42of the cathode extends-outwardly some littleA distance beyond the peripheral edge of the active surface 43 of the anode. This arrangement makes allowance for the fact that the voiume of hydrogen generated at the cathode is twice that of the oxygen generatedat the anode. Moreover, the curvature of the inner surface of the cathode may continue to the eXtreme edge 44 thereof, as contrasted with the substantially plane character of the active anode surface 43, an arrangement which has advantages under sonfe conditions. The dividingedge of the'separator disc 45 may be positioned somewhat closer to the anode surface than the cathode surface, thus providing a larger channel for the cathode surface and thence past the separator disc to the place of discharge.

What I claim is:

l. Electrolytic apparatus comprising, in combination, a plurality of electrode couples each consisting of a pair of opposed tubular electrodes operatively spaced apart, and an electrolyte supply chamber common to all of said couples, each of said electrodes affording communication between the interior and the exterior of said chamber.

2. Electrolytic apparatus comprising, in combination, a plurality of electrode couples each consisting of a pair of opposed tubular electrodes operatively spaced apart, and electrolyte supply means common to said couples.

3. Electrolytic apparatus comprising, in comblnation, a plurality of tubular generator units having electrolyte intakes and separate anolyte and c'atholyte discharge outlets, an electrolyte supply chamber into which the intakes of said units open," and separate dlscharge chambers into which said anolyte and catholyte discharge outlets respectively open.

4. llectrolytic apparatus comprising, in combinatlon, a casing, two partitions divid- 1ng the interior of said casing into an intermed1ate and two end chambers, and a plurality of electrode couples each consistingof a pa1r of cooperating tubular electrode members supported by said partitions in opposed spaced relation within said intermediate chamber'and affording communication with said end chambers.

5. Electrolytic apparatus comprising, in comblnatlon, a casing interiorly divided into an anolyte discharge'chamber, a. catholyte discharge chamber, and an electrolyte supply chamber, a plurality 0f tubular anode deylces mounted within said casing and affordlng communication between said supply chamber and said anolyte discharge chamber,

a plurality of tubular cathode devices mountl ed within said casing and affording communication between said supply chamber and said catholyte discharge chamber, said anode 'and cathode devices being positioned 1n cooperating pairs or couples with ends operatively adjacent to provide opposed annular active electrode surfaces of opposite polarity, an inlet pipe for introducing electrolyte into said supply chamber, and discharge pipes leading from said discharge chambers.

6. Electrolytic apparatus comprising, in combination, an electrolyte supply chamber, and a plurality of apertured electrode' couples each opening into said chamber, receiving electrolyte from said chamber and discharging it outside said chamber.

7. Electrolytic apparatus comprising, in combination, an electrolyte chamber, and a plurality of apertured electrode couples each aiording communication between the interior and the exterior of said chamber.

8. Electrolytic apparatus comprising electrode devices having closely adjacent relatively narrow electrode surfaces of unequal area coperating to form a couple, means for causing electrolyte to flow across and between said surfaces, and means adjacent said surfaces for dividing eiiiuent electrolyte into separate portions.

9. Elect-rolytic apparatus comprising, in combination, two tubular electrode devices having terminal annular electrode surfaces of unequal effective area disposed operatively adjacent to form a couple.

l0. Electrolytic apparatus comprising, in

combination, two coaxially arranged tubular electrode devices having annular electrode surfaces of unequal area operatively adjacent to form a couple, the space between said surfaces being unobstructed.

ll. Electrolytic apparatus comprising, in combination, two vcoaxially arranged tubular electrode devices having annular electrode surfaces of unequal area operatively adjacent to form a couple, the space between said surfaces being unobstructed, means for causing electrolyte to flow across said surfaces toward their common axis, and means for dividing the inflowing electrolyte into separate portions and guiding them into different paths.

l2. Electrolytic apparatus comprising, in combination., an electrolyte supply chamber, and a plurality of electrode couples extending therein, each couple consisting of a pair of electrodes having opposed annular faces.

13. Electrolytic apparatus comprising, in combination, an electrolyte chamber, and a plurality of hollow electrodes extending therein, said electrodes affording communication between the interior and exterior of said chamber.

In testimony whereof I hereunto affix my signature.

JAMES NORMAN SMITH, 

